Optimize handlers for large datasets

**Description**
Currently validation lacks proper search support.

**Proposed solution**
Add configurable search with sensible defaults.

**Priority**: Low/Medium

No file, test, or entry point is named. Start by locating the validation handlers and the path that processes large datasets, then clarify the expected configurable search behavior and defaults with the maintainer. Done means the agreed search behavior is implemented and covered by relevant tests.

Written by the indexing model from the issue text.